1. Field of the Invention
The present invention relates to a mobile IP communication scheme, and more particularly, to a mobile computer device capable of carrying out communications while moving over a plurality of inter-connected networks, a mobile computer management device and a mobile information management device for protecting necessary information to the mobile computer device and relaying data packets transmitted to the mobile computer device according to the need, and a communication control method used by these devices.
2. Description of the Background Art
In conjunction with availability of a computer system in smaller size and lower cost and a more enriched network environment, the use of computer system has been rapidly expanded into variety of fields, and there is also a transition from a centralized system to a distributed system. In this regard, in recent years, because of the advance and spread of the computer network technology in addition to the progress and improved performance of the computer system itself, it has become possible to realize not only a sharing of resources such as files and printers within an office but also communications (electronic mail, electronic news, file transfer etc.) with outside of an office or organization, and these communications are now widely used.
In particular, in recent years, the use of the world""s largest computer network called Internet has become very popular, and there are new computer businesses for connecting to the Internet and utilizing open information and services, or for providing information and services to external users who make accesses through the Interest. In addition, new technological developments are made in relation to the use of the Internet.
Also, in conjunction with the spread of such networks and the advance of small portable terminal technology, there are technological developments regarding the mobile computing. In the mobile computing, a user carries along a portable computer or terminal and makes communications while moving over networks and there is a need for a scheme that manages a changing address of a mobile computer on a network during such a communication in order to route the communication content correctly. As a protocol for supporting such mobile communications, there is a scheme called mobile IP which is currently in a process of being standardized by the mobile-IP working group of the IETF (see IETF RFC2002, IP mobility support (C. Perkins)).
In the mobile IP, a module (home agent) for managing a location information of the mobile computer is provided in a network to which the mobile computer originally belongs, and when the mobile computer moves, the mobile computer sends a registration message indicating a current location to this home agent. When this registration message is received, the home agent carries out a routing control in which the home agent acquires data destined to the mobile computer that is transmitted to an original address (home address) of the mobile computer and transfers it to the current location of the mobile computer automatically by encapsulating it inside a packet destined to the registered current location address of the mobile computer.
FIG. 19 shows this situation where a home agent (HA) 105 is playing this role with respect to a mobile computer 102. Namely, when the mobile computer 102 moves from a home network 1a to a network 1b, the mobile computer 102 sends a registration message indicating a current location to the home agent 105, and the home agent 105 that received this registration message carries out a control for transferring data transmitted to the original address (home address) of the mobile computer 102 to the current location of the mobile computer 102.
Now, in the case of carrying out a communication from a visited site using this mobile IP scheme, the mobile computer will always receive data through the home agent of the home network. However, when the mobile computer moves far away from the home agent, there is a possibility for considerably lowering the performance of a communication program because packets are always routed via the home agent. This is the case not only when the physical distance between the visited site network and the home network is large but also when a route between the visited site network and the home network involves a path at which many data packets are jamming.
Namely, the communication method using the mobile IP has a scalability that guarantees a continual communication regardless of a location on the IP network to which the mobile computer moves, but it does not necessarily guarantee that the communication can be continued comfortably.
Also, another advantage of the mobile IP scheme is that it is possible to make accesses to various resources of the home site by using attributes given before moving, because accesses are made by packets originating from an address in the home network (home address) even when the mobile computer is located at the visited site. However, in general, in the case of making an access to an information unrelated to the home site (as in the case of making an access to a Web page on the third party network or to a local printer at the visited site, for example), there is no need to carry out communications via the home network using the mobile IP, and it suffices to just use an address (temporal address) that is temporarily assigned at the visited site.
Yet, there are some recent network communication softwares in which a proper communication cannot be realized by just acquiring a temporal address alone at the visited site. For example, at a site where a network is constructed using private addresses, an address conversion is carried out by using a server called proxy server at a time of making an access to an external site, so that it is necessary for the communication software to make a setting of an IP address of the proxy server. Also, in the case where a DNS (Domain Name System) server is provided at each site, the use of the DNS server can be convenient as it becomes possible to make an access to a resource using a host name rather than an IP address, but in such a case it is also necessary to make a setting of an IP address of the DNS server in address.
In other words, in the case of trying to receive a network service using a temporal address borrowed from some network, without using the mobile IP, it is necessary to obtain a resource information (such as that of the proxy server or the DNS server mentioned above) of that network. Such an information is freely obtainable for a network manager in general, but for a general user, it is difficult to handle such an information and it is also difficult to make a proper setting of such an information at a proper portion of the communication program.
As described above, in general, in the case of supporting a mobile computer using the mobile IP scheme, communications with a home agent of a home network can be very difficult depending on a moved location of the mobile computer, and this fact can adversely affect the operation performance of a communication program in some cases.
On the other hand, when a scheme for acquiring a temporal address at a visited site and using it in carrying out communications is adopted, it becomes necessary to obtain various kinds of network configuration information (such as that of a proxy server or a DNS server in the case of WWW access, or that of a Certificate Server in the case of SSL (data encryption) communication, for example), besides an address. In order to make a proper setting of such an information, a thorough understanding of a network environment at a visited site is required so that it is quite difficult to do for a beginner who has no knowledge regarding networks.
Thus, conventionally, in the case of using a program such a browser while moving over networks, it has been necessary to make a proper setting of various kinds of environmental information in addition to acquiring an IP address at a visited site, and it has been very inconvenient especially for an end-user who has no knowledge regarding networks.
As a possible solution to this problem, there has been a proposition of a scheme called mobile IP in which an environment of a home network to which a host is originally connected can be utilized even at a visited site. In this scheme, there is no need for making an extra setting, but the moving to a location far away from the home network can be disadvantageous from a viewpoint of the performance of packet exchange with the home network, and can also adversely affect the operation performance of programs.
It is therefore an object of the present invention to provide a mobile computer device and a communication control method, wherein when a mobile compute device capable of carrying out communications while moving over inter-connected networks (such as Internet or Intranet) operates a program at a visited site, it is possible to construct a mobile IP communication environment in which a visited site network or a nearby network is regarded as a home network.
It is another object of the present invention to provide a mobile computer device, a mobile computer management device, a mobile information management device and a communication control method, wherein when a mobile computer device capable of carrying out communications while moving over inter-connected networks (such as Internet or Intranet) operates a program at a visited site, it is possible to carry out a setting of a communication program such as browser suitable for a visited site network or a nearby network automatically.
It is another object of the present invention to provide a mobile computer management device to be provided in some network and a communication control method, which are capable of providing an environment with respect to a mobile computer device capable of carrying out communications while moving over inter-connected networks (such as Internet or Intranet), in which it is possible to construct a mobile IP communication environment where the mobile computer device can regard a network to which the mobile computer management device belongs as a home network.
According to one aspect of the present invention there is provided a mobile computer device capable of carrying out communications while moving over inter-connected networks, comprising: an exchange processing unit for exchanging a message with a management device provided in a visited site network or a nearby network to which the mobile computer device is connected through a network from a visited site, so as to acquire a network configuration information of the visited site network or the nearby network, the management device having a management function for enabling the communication by the mobile computer device at the visited site; and a setting unit for setting the network configuration information acquired according to the message in a communication program to be used in carrying out the communications.
According to another aspect of the present invention there is provided a mobile computer device capable of carrying out communications while moving over inter-connected networks, comprising: a selection unit for selecting one of a plurality of mobile computer management devices provided in a plurality of networks, each mobile computer management device having functions for managing a moving location of each registered mobile computer device and transferring data destined to each registered mobile computer device to its moving location; and a message exchange unit for exchanging a message with a selected mobile computer management device from a visited site, so as to register the mobile computer device to the selected mobile computer management device as a mobile node which regards one network to which the selected mobile computer management device belongs as a home network.
According to another aspect of the present invention there is provided a mobile computer management device to be provided in a prescribed network among inter-connected networks, comprising: an address leasing unit for leasing a temporal address to be used by a mobile computer in response to a request message from the mobile computer; a moving management unit for receiving a registration message from the mobile computer to which the the temporal address is leased, and registering and managing a correspondence between the temporal address and a current location of the mobile computer; a network configuration information response unit for returning to the mobile computer one message containing a network configuration information of one network to which the mobile computer management device belongs or a resource server information that has the network configuration information; and a data transfer unit for capturing data transmitted to the temporal address, and transferring the data to the current location of the mobile computer according to the registered correspondence.
According to another aspect of the present invention there is provided a mobile computer management device, to be provided in a prescribed network among inter-connected networks, for managing mobile IP communications of a registered mobile computer, comprising: an address leasing unit for leaving a temporal home address to be used by a mobile computer located outside a subnet to which the mobile computer management device is connected, in response to a request message from the mobile computer; and a registration unit for registering the mobile computer as a mobile node to be managed by the mobile computer management device, in response to a registration message from the mobile computer to which the temporal home address is leased.
According to another aspect of the present invention there is provided a mobile information management device for use in conjunction with a mobile computer management device which is provided in a prescribed network among inter-connected networks and managing mobile IP communications of a registered mobile computer, the mobile information management device comprising: an address leasing unit for leasing a temporal address to be used by a mobile computer located outside a subnet to which the mobile information management device is connected, in response to a request message from the mobile computer; and an information providing unit for providing a network configuration information of a network to which the mobile information management device belongs or a resource server information that has the network configuration information, to the mobile computer.
According to another aspect of the present invention there is provided a communication control method for a mobile computer device capable of carrying out communications while moving over inter-connected networks, the method comprising the steps of: exchanging a message with a management device provided in visited site network or a nearby network to which the mobile computer device is connected through a network from a visited site, so as to acquire a network configuration information of the visited site network or the nearby network, the management device having a management function for enabling the communications by the mobile computer device at the visited site; and setting the network configuration information acquired according to the message in a communication program to be used in carrying out the communications.
According to another aspect of the present invention there is provided a communication control method for a mobile computer device capable of carrying out communications while moving over inter-connected networks, the method comprising the steps of: selecting one of a plurality of mobile computer management devices provided in a plurality of networks, each mobile computer management device having functions for managing a moving location of each registered mobile computer device and transferring data destined to each registered mobile computer device to its moving location; and exchanging a message with a selected mobile computer management device from a visited site, so as to register the mobile computer device to the selected mobile computer management device as a mobile node which regards one network to which the selected mobile computer management device belongs as a home network.
According to another aspect of the present invention there is provided a communication control method for a mobile computer management device to be provided in a prescribed network among inter-connected networks, the method comprising the steps of: leasing a temporal address to be used by a mobile computer in response to a request message from the mobile computer; receiving a registration message from the mobile computer to which the temporal address is leased, and registering and managing a correspondence between the temporal address and a current location of the mobile computer; returning to the mobile computer one message containing a network configuration information of one network to which the mobile computer management device belongs or a resource server information that has the network configuration information; and capturing data transmitted to the temporal address, and transferring the data to the current location of the mobile computer according to the registered correspondence.
According to another aspect of the present invention there is provided a communication control method for a mobile computer management device, to be provided in a prescribed network among inter-connected networks, for managing while IP communications of a registered mobile computer, the method comprising the steps of: leasing a temporal home address to be used by a mobile computer located outside a subnet to which the mobile computer management device is connected, in response to a request message from the mobile computer; and registering the mobile computer as a mobile node to be managed by the mobile computer management device, in response to a registration message from the mobile computer to which the temporal home address is leased.
According to another aspect of the present invention there is provided a communication control method for a mobile information management device for use in conjunction with a mobile computer management device which is provided in a prescribed network among inter-connected networks and managing mobile IP communications of a registered mobile computer, the method comprising the steps of: leasing a temporal address to be used by a mobile computer located outside a subnet to which the mobile information management device is connected, in response to a request message from the mobile computer; and providing a network configuration information of a network to which the mobile information management device belongs or a resource server information that has the network configuration information, to the mobile computer.
According to another aspect of the present invention there is provided an article of manufacture, comprising: a computer usable medium having a computer readable program code means embodied therein for causing a computer to function as a mobile computer device capable of carrying out communications while moving over inter-connected networks, the computer readable program code means includes: first computer readable program code means for causing said computer to exchange a message with a management device provided in a visited site network or a nearby network to which the mobile computer device is connected through a network from a visited site, so as to acquire a network configuration information of the visited site network or the nearby network, the management device having a management function for enabling the communications by the mobile computer device at the visited site; and second computer readable program code means for causing said computer to set the network configuration information acquired according to the message in a communication program to be used in carrying out the communications.
According to another aspect of the present invention there is provided an article of manufacture, comprising: a computer usable medium having computer readable program code means embodied therein for causing a computer to function as a mobile computer device capable of carrying out communications while moving over inter-connected networks, the computer readable program code means includes: first computer readable program code means for causing said computer to select one of a plurality of mobile computer management devices provided in a plurality of networks, each mobile computer management device having functions for managing a moving location of each registered mobile computer device and transferring data destined to each registered mobile computer device to its moving location; and second computer readable program code means for causing said computer to exchange a message with a selected mobile computer management device from a visited site, so as to register the mobile computer device to the selected mobile computer management device as a mobile node which regards one network to which the selected mobile computer management device belongs as a home network.
According to another aspect of the present invention there is provided an article of manufacture, comprising: a computer usable medium having computer readable program code means embodied therein for causing a computer to function as a mobile computer management device to be provided in a prescribed network among inter-connected networks, the computer readable program code means includes: first computer readable program code means for causing said computer to lease a temporal address to be used by a mobile computer in response to a request message from the mobile computer; second computer readable program code means for causing said computer to receive a registration message from the mobile computer to which the temporal address is leased, and register and manage a correspondence between the temporal address and a current location of the mobile computer; third computer readable program code means for causing said computer to return to the mobile computer one message containing a network configuration information of one network to which the mobile computer management device belongs or a resource server information that has the network configuration information; and fourth computer readable program code means for causing said computer to capture data transmitted to the temporal address, and transfer the data to the current location of the mobile computer according to the registered correspondence.
According to another aspect of the present invention there is provided an article or manufacture, comprising: a computer usable medium having computer readable program code means embodied therein for causing a computer to function as a mobile computer management device, to be provided in a prescribed network among inter-connected networks, for managing mobile IP communications of a registered mobile computer, the computer readable program code means includes: first computer readable program code means for causing said computer to lease a temporal home address to be used by a mobile computer located outside a subnet to which the mobile computer management device is connected, in response to a request message from the mobile computer; and second computer readable program code means for causing said computer to register the mobile computer as a mobile node to be managed by the mobile computer management device, in response to a registration message from the mobile computer to which the temporal home address is leased.
According to another aspect of the present invention there is provided an article of manufacture, comprising: a computer usable medium having computer readable program code means embodied therein for causing a computer to function as a mobile information management device for use in conjunction with a mobile computer management device which is provided in a prescribed network among inter-connected networks and managing mobile IP communications of a registered mobile computer, the computer readable program code means includes: first computer readable program code means for causing said computer to lease a temporal address to be used by a mobile computer located outside a subnet to which the mobile information management device is connected, in response to a request message from the mobile computer; and second computer readable program code means for causing said computer to provide a network configuration information of a network to which the mobile information management device belongs or a resource server information that has the network configuration information, to the mobile computer.